Virtually nothing is known about the physiology or metabolism of renal basement membrane constituents or constituents from renal tubular cells. This proposal is designed to study the physiology of renal constituents by developing sensitive and quantitative radioimmunoassays for basement membrane and renal tubular materials. The normal physiologic levels of these materials in the circulation and excretion into the urine will be established. Events (traumatic, ischemic, immunologic, infectious) which could potentially influence the levels of these materials in the body fluids will be quantitated and related to their nephritogenic potential. In addition, the radioimmunoassay should be extremely useful in following basement membrane and tubular constituents during their isolation and subsequent identification of their structural and functional relationships. In order to extend our knowledge of the introduction of nephritis, it is essential to understand the events responsible for the initiation of immune responses to renal constituents involved in the immunopathogenesis of both glomerulonephritis and tubular interstitial nephritis. BIBLIOGRAPHIC REFERENCES: Theofilopoulos, A.N. Wilson, C. B. and Dixon, F.J.: The Raji cell radioimmune assay for detecting immune complexes in human sera. J. Clin. Invest. 57:169, 1976. Baylis, C., Ichikawa, I., Willis, W. T., Wilson, C. B., and Brenner, B. M.: Dynamics of glomerular ultrafiltration. IX. Effects of plasma protein concentration. Am. J. Physiol. 232:F58, 1977.